# Role of Microglia in Neurodegeneration -Effect of ApoE

> **NIH NIH R01** · NEW YORK UNIVERSITY SCHOOL OF MEDICINE · 2024 · $680,533

## Abstract

Project Summary
Like Alzheimer's disease, prion diseases (prionoses) are conformational disorders, in which deposition of
misfolded proteins is accompanied by microglia neurodegenerative phenotype (MGnD) displaying mixed
phagocytic and inflammatory properties. Prion mouse models with misfolded protein driven neurodegeneration
and activated glia response can be used to uncover Alzheimer's disease relevant pathomechanisms. APOE ε4
allele is the foremost risk factor in sporadic Alzheimer's disease, increasing its odds by 3 and 15-fold in hetero
and homozygotes, respectively. APOE encodes apolipoprotein (apo) E, which controls brain lipid homeostasis
and modulates Alzheimer's disease risk through isoform-specific effect on clearance and deposition of soluble
Aβ. ApoE is expressed by astrocytes in form of apoE/HDLs and also by MGnD as lipid-poor particles. Differential
contributions of these two apoE pools to MGnD properties remain unclear. While lipidated apoE may facilitate
clearance of misfolded proteins, expression of lipid-poor apoE by MGnD is linked to their pro-inflammatory
properties, which also are differentially controlled by APOE genotype. In prionoses, accumulation of toxic PrPSc
protein is the culprit of pathogenesis. Microglia undergo activation early in the course of disease and exert
opposing roles in PrPSc mediated neurodegeneration. While clearance of PrPSc has a disease-limiting effect,
microglia-driven neuroinflammation is deleterious to neurons. Involvement of apoE in prion pathogenesis has
not been established, though there is evidence for ~2-fold higher risk of sporadic Creutzfeldt-Jakob disease
(CJD) in ε4 carriers. Our preliminary work shows increased brain apoE level in prion infected mice along with
reduced apoE expression in astrocytes and increased expression in activated microglia. The overall effect of
apoE in prionoses is beneficial as global Apoe KO exacerbates prion pathology by aggravating the vicious cycle
of neuronal death and neuroinflammation. In Apoe-/- mice, clearance of PrPSc and dying neurons by MGnD
becomes inefficient while neuronal debris exaggerate MGnD phenotype, release of inflammatory cytokines, and
induce A1 neurotoxic astrocytes. Our studies also suggest, apoE effect in prionoses is isoform dependent. ε4/ε4
targeted replacement (TR) mice have shorter disease incubation time, increased pathology load and microglia
hyperactivation compared to ε3/ε3 and ε2/ε2 mice. This preliminary work led us to hypothesize 1) apoE
involvement in prion pathogenesis is by control of microglia response to PrPSc mediated neurodegeneration; 2)
apoE-based approaches have therapeutic merit in prionoses; and 3) effect of apoE in human prionoses is isoform
dependent. These hypotheses shall be explored in grant's specific aims. Aim I will assess the role of astrocyte
vs. microglia-expressed apoE on PrPSc mediated neurodegeneration in mice with cell-specific conditional Apoe
knock out. Aim II will assess whether regulating lipid...

## Key facts

- **NIH application ID:** 10795857
- **Project number:** 5R01AG075840-03
- **Recipient organization:** NEW YORK UNIVERSITY SCHOOL OF MEDICINE
- **Principal Investigator:** MARTIN Joseph SADOWSKI
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $680,533
- **Award type:** 5
- **Project period:** 2022-06-15 → 2027-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10795857

## Citation

> US National Institutes of Health, RePORTER application 10795857, Role of Microglia in Neurodegeneration -Effect of ApoE (5R01AG075840-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10795857. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*